9781422273098

THE WORLD OF PHYSICS When you throw a ball across the room, how does it move? It might go straight across the room at first, but then curve down. When it reaches a wall, it will bounce off. Eventually, it will stop moving and sit still. The laws of physics can explain every movement this ball makes. Physicists study these laws to try to figure out what causes these movements. As the ball flies across the room, different forces act upon it. One force is gravity—the invisible force that pulls all objects on Earth toward the center of the Earth. It is what keeps you on the ground and pulls you back down after you jump up. Another force is the one you are applying as you toss the ball. Finally, air resistance plays a role. Even though air might seem transparent or invisible, it is actually made up of tiny particles. Think of the way you swim through a pool. As you push your arms and legs, the water works against you. Air resistance is just like that, except it is easier to move through air than water. Physicists apply their understanding of all these forces while studying how objects move and why. The smallest of these objects are subatomic particles. These particles are the smallest unit known to humans, and they cannot be seen with the naked eye. The largest objects a physicist might study are planets, galaxies, or even the entire universe. In this way, physicists study everything that could ever possibly exist. Physicists are always trying to find out more about how the world works and why. Physics can be applied to anything you do. Whether you are writing on a piece of paper, swimming in the ocean, or watching the moon in the sky, physics has allowed all these things to happen. As you go about your daily routine, pay special attention to what you do. Feel your feet push against the ground as you walk. Notice how the sun’s rays seem to warm your skin. Watch your chest rise and fall as you breathe in and out. All of this is caused by physics! Many physicists become fascinated with the world when they are young. They continually ask questions: Why are there stars in the sky? What causes the earth to revolve around the sun? How do birds and airplanes fly? Physics offers answers to all of these questions and more. And even with all of these answers, there are WOMEN IN PHYSICS

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